Geographic disparities in trends of thyroid cancer incidence and mortality from 1990 to 2019 and a projection to 2030 across income-classified countries and territories

Background The rising incidence of thyroid cancer (TC) has generated growing concern globally; yet there are no studies examining whether this incidence was followed by a rise in related mortality. We aimed to comprehensively quantify current trends and future projections of TC incidence and mortality, and to explore the association between the TC burden and socioeconomic inequality in different income strata. Methods We obtained incidence and mortality data on TC and population from the 2019 Global Burden of Disease (GBD) study and the United Nations’ World Population Prospects 2022. We applied an age-period-cohort (APC) model to estimate the overall annual percentage change (net drift) and age, period, and cohort effects from 1990 to 2019, and also constructed a Bayesian APC model to predict the TC burden through 2030. Results Over a third of global TC cases belonged to the high-income group. From 1990 to 2019, net drifts of TC incidence were >0 in all income groups, while a modest reduction (net drift <0) in mortality was observed in most income groups, except for the lower-middle-income group. Unfavourable age, period, and cohort effects were most notable in Vietnam, China, and Korea. The age-standardised incidence rate (ASIR) is predicted to increase whereas the age-standardized mortality rate (ASMR) is expected to decrease globally between 2020 and 2030, with geographic heterogeneity being detected across income groups. We observed a positive correlation between ASIR and universal health coverage index and health worker density, but a negative one between ASMR and the two indicators, primarily in upper-middle-income and high-income countries. Conclusions Opposite patterns in incidence and mortality of TC raise concerns about overdiagnosis, particularly in upper-middle-income and high-income countries. Discrepancies in the distribution of health service accessibility, including diagnostic techniques and therapeutic care, should be addressed by narrowing health inequalities in the TC burden across countries.

. Predicted number (in thousand) of thyroid cancer cases from 1990 to 203016 Table S7.Predicted number (in thousand) of thyroid cancer deaths from 1990 to 203017 Table S8.Age-standardized rates (per 100,000) of incidence and mortality for thyroid

Data Inputs
For all data inputs from multiple sources that are synthesized as part of the study: Describe how the data were identified and how the data were accessed.2-3 4 Specify the inclusion and exclusion criteria.Identify all ad-hoc exclusions. 3 Provide information on all included data sources and their main characteristics.For each data source used, report reference information or contact name/institution, population represented, data collection method, year(s) of data collection, sex and age range, diagnostic criteria or measurement method, and sample size, as relevant.

2-3 6
Identify and describe any categories of input data that have potentially important biases (e.g., based on characteristics listed in item 5). 2 For data inputs that contribute to the analysis but were not synthesized as part of the study:

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Data analysis 9
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3-4 10
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3-4 11
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3-4 12
Provide the results of an evaluation of model performance, if done, as well as the results of any relevant sensitivity analysis.

N/A
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3-4 14
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Results and Discussion 15
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4-9 16
Report a quantitative measure of the uncertainty of the estimates (e.g.uncertainty intervals).

4-9 17
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9-12 18
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Supplementary Method. Calculation of estimated annual percentage change
We calculated estimated annual percentage change (EAPC) of age-standardized incidence rate (ASIR) from 1990 to 2019 in 201 countries and territories.A liner regression was fitted with the natural logarithm, ie, , where y is ln ASIR, x is the calendar year, and ε is the error term.The EAPC was defined as 100×(exp (β)-1).The positive values of EAPC and the lower boundary of 95% confidence interval (CI) indicated an upward trend of age-standardized rates over the time interval, while the negative values of EAPC and the upper boundary of 95% CI indicated an opposite downward trend.

Figure S1 .
Figure S1.The estimated annual percentage change of thyroid cancer age-standardized incidence rate in 31 low-income countries from 1990 to 2019

Figure S2 .
Figure S2.The estimated annual percentage change of thyroid cancer age-standardized incidence rate in 47 lower-middle-income countries from 1990 to 2019

Figure S3 .
Figure S3.The estimated annual percentage change of thyroid cancer age-standardized incidence rate in 59 upper-middle-income countries from 1990 to 2019

Figure S4 .
Figure S4.The estimated annual percentage change of thyroid cancer age-standardized incidence rate in 64 high-income countries from 1990 to 2019

Table S1 .
201 countries and territories classified by the World Bank

Table S2 .
Universal health coverage index and human resources value for health in 201 income-stratified countries and territories

Table S6 .
Predicted number (in thousand) of thyroid cancer cases from 1990 to 2030

Table S7 .
Predicted number (in thousand) of thyroid cancer deaths from 1990 to 2030